The Influence of Tiw Barrier Layer on Reliability of AlCu and AlSiCu Interconnects

1995 ◽  
Vol 391 ◽  
Author(s):  
S. Kordic ◽  
R.A.M. Wolters ◽  
R.A. Augur ◽  
A.G. Dirks
Keyword(s):  
Stress Relaxation ◽  
Grain Boundaries ◽  
Barrier Layer ◽  
Void Formation ◽  
Diffusion Paths ◽  
Si Content

AbstractThe influence of a TiW barrier layer on the stress-voiding behavior of AlCu and AlSiCu interconnects is investigated. The results are compared to the same alloys deposited on SiO2- In both cases, AlCu exhibits a notably better voiding behavior compared to AlSiCu. In the case in which the alloys are directly deposited on the TiW barrier without breaking vacuum between TiW and Al(Si)Cu depositions, a significant improvement of the voiding behavior of both alloys is observed. Compared to AlCu, AlSiCu shows worse voiding behavior due to the presence of Si precipitates, which introduce significant extra dislocations and defects in the Al grains. These dislocations and defects are diffusion paths which assist stress relaxation and void formation. In the presence of a TiW barrier part of the Si content of the AlSiCu is consumed during the anneal by the Al-TiW interface, which results in a decreased number of dislocations and defects within the Al grains, and an improved voiding behavior compared to AlSiCu on SiO2-Furthermore, W and Ti diffuse into the grain boundaries of both alloys. The presence of W and Ti in the grain boundaries reduces the amount of Cu depletion from within the grains, which makes both alloys more resistant to stress voiding. The above is supported by Auger and TEM results. The electromigration results of the alloys in question are presented. These show that also with respect to electromigration AlCu is the preferred alloy both on TiW and SiO2.

scholarly journals Material Properties of Zr–Cu–Ni–Al Thin Films as Diffusion Barrier Layer

Crystals ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 540 ◽  
Author(s):  
Po-Hsien Sung ◽  
Tei-Chen Chen
Keyword(s):  
Thin Film ◽  
Grain Boundaries ◽  
Barrier Layer ◽  
Fast Diffusion ◽  
Quenching Rate ◽  
Cu Metallization ◽  
Diffusion Barrier Layer ◽  
Diffusion Paths ◽  
Reliability Issue ◽  
Almost All

Due to the rapid increase in current density encountered in new chips, the phenomena of thermomigration and electromigration in the solder bump become a serious reliability issue. Currently, Ni or TiN, as a barrier layer, is widely academically studied and industrially accepted to inhibit rapid copper diffusion in interconnect structures. Unfortunately, these barrier layers are polycrystalline and provide inadequate protection because grain boundaries may presumably serve as fast diffusion paths for copper and could react to form Cu–Sn intermetallic compounds (IMCs). Amorphous metallic films, however, have the potential to be the most effective barrier layer for Cu metallization due to the absence of grain boundaries and immiscibility with copper. In this article, the diffusion properties, the strength of the interface between polycrystalline and amorphous ZrCuNiAl thin film, and the effects of quenching rate on the internal microstructures of amorphous metal films were individually investigated by molecular dynamics (MD) simulation. Moreover, experimental data of the diffusion process for three different cases, i.e., without barrier layer, with an Ni barrier layer, and with a Zr53Cu30Ni9Al8 thin film metallic glass (TFMG) barrier layer, were individually depicted. The simulation results show that, for ZrCuNiAl alloy, more than 99% of the amorphous phase at a quenching rate between 0.25 K/ps and 25 K/ps can be obtained, indicating that this alloy has superior glass-forming ability. The simulation of diffusion behavior indicated that a higher amorphous ratio resulted in better barrier performance. Moreover, a very small and uniformly distributed strain appears in the ZrCuNiAl layer in the simulation of the interfacial tension test; however, almost all the voids are initiated and propagated in the Cu layer. These phenomena indicate that the strength of the ZrCuNiAl/Cu interface and ZrCuNiAl layer is greater than polycrystalline Cu. Experimental results show that the Zr53Cu30Ni9Al8 TFMG layer exhibits a superior barrier effect. Almost no IMCs appear in this TFMG barrier layer even after aging at 125 °C for 500 h.

scholarly journals Preferential void formation at crystallographically ordered grain boundaries in nanotwinned copper thin films

2015 ◽  
Vol 96 ◽  
pp. 284-291 ◽  
Author(s):  
Thomas LaGrange ◽  
Kazuto Arakawa ◽  
Hidehiro Yasuda ◽  
Mukul Kumar
Keyword(s):  
Thin Films ◽  
Grain Boundaries ◽  
Void Formation

Effect of mass transport along interfaces and grain boundaries on copper interconnect degradation

2004 ◽  
Vol 812 ◽  
Author(s):  
Ehrenfried Zschech ◽  
Moritz A. Meyer ◽  
Eckhard Langer
Keyword(s):  
Mass Transport ◽  
Grain Boundaries ◽  
Void Formation ◽  
Degradation Process ◽  
Copper Interconnects ◽  
Second Phase ◽  
Copper Interconnect ◽  
Void Evolution ◽  
Two Phases

AbstractIn-situ SEM electromigration studies were performed at fully embedded via/line interconnect structures to visualize the time-dependent void evolution in inlaid copper interconnects. Void formation, growth and movement, and consequently interconnect degradation, depend on both interface bonding and copper microstructure. Two phases are distinguished for the electromigration-induced interconnect degradation process: In the first phase, agglomerations of vacancies and voids are formed at interfaces and grain boundaries, and voids move along weak interfaces. In the second phase of the degradation process, they merge into a larger void which subsequently grows into the via and eventually causes the interconnect failure. Void movement along the copper line and void growth in the via are discontinuous processes, whereas their step-like behavior is caused by the copper microstructure. Directed mass transport along inner surfaces depends strongly on the crystallographic orientation of the copper grains. Electromigration lifetime can be drastically increased by changing the copper/capping layer interface. Both an additional CoWP coating and a local copper alloying with aluminum increase the bonding strength of the top interface of the copper interconnect line, and consequently, electromigration-induced mass transport and degradation processes are reduced significantly.

The Microstructural Nature of Electromigration and Mechanical Stress Voids in Integratedcircuit Interconnect

1993 ◽  
Vol 309 ◽  
Author(s):  
Jamie H. Rose ◽  
Terry Spooner
Keyword(s):  
Grain Boundary ◽  
Integrated Circuit ◽  
Boundary Diffusion ◽  
Void Formation ◽  
Parallel Line ◽  
Relative Displacement ◽  
Test Conditions ◽  
Line Array ◽  
Interconnect Reliability ◽  
Diffusion Paths

AbstractIt is well known that stress and electromigration induced voiding is of major concern for integrated circuit interconnect reliability. However, there has been little systematiccharacterization of void morphology and crystallography in ever more technologically important narrow, “near-bamboo” conducting lines. Prior reports indicate thatvoids are typically wedge or slit shaped, with failure often associated with slit voids.Void face habit plane is most often reported to be {111}. Wedge and slit void morphology and crystallography have been studied in comb/serpentine and parallel line array test structures. In virtually all cases, void faces are {111} oriented. In contrast to earlier studies, intragranular wedge stress voids have been observed. All electromigration opens were due to slit voids; these were typically intragranular, in contradiction to current theories of void formation, and likely are mechanical fractures. Under accelerated test conditions, non-grain boundary diffusion paths appear to operate at distances of tens of micrometers. Relative displacement between wedge voids and attached grain boundaries occurs where a wedge face lies on a near common {111} plane for the two grains. It is suggested that slit voids are intragranular under both stress and electromigration conditions and likely associated with local interconnect depassivation. Based solely on appearance and crystallography, no void can uniquely be identified as due to stress alone or electromigration alone.

Carbon diffusion paths and segregation at high-angle tilt grain boundaries inα-Fe studied by using a kinetic activation-relation technique

2018 ◽  
Vol 97 (5) ◽  
Author(s):  
Oscar A. Restrepo ◽  
Normand Mousseau ◽  
Mickaël Trochet ◽  
Fedwa El-Mellouhi ◽  
Othmane Bouhali ◽  
...  
Keyword(s):  
Grain Boundaries ◽  
Carbon Diffusion ◽  
High Angle ◽  
Diffusion Paths

Effect of surface area of grain boundaries on stress relaxation behavior in pure copper over wide range of grain sizes

2020 ◽  
Vol 794 ◽  
pp. 139585
Author(s):  
Yurina Suzuki ◽  
Kota Ueno ◽  
Kodai Murasawa ◽  
Yoshinori Kusuda ◽  
Masato Takamura ◽  
...  
Keyword(s):  
Stress Relaxation ◽  
Grain Boundaries ◽  
Surface Area ◽  
Pure Copper ◽  
Relaxation Behavior ◽  
Stress Relaxation Behavior ◽  
Grain Sizes ◽  
Wide Range ◽  
Effect Of Surface

Impact of Microstructure of Alternative Al-Si-V-Pd Alloy Films on Interconnect Reliability, Compared to Al-Si-Cu

1994 ◽  
Vol 337 ◽  
Author(s):  
A.G. Dirks ◽  
R.A. Augur ◽  
S. Kordić ◽  
R.A.M. Wolters
Keyword(s):  
Grain Boundaries ◽  
Integrated Circuit ◽  
Void Formation ◽  
Quaternary Alloy ◽  
Alloy Films ◽  
Cu Alloy ◽  
Transmission Electron ◽  
Pd Alloy ◽  
Interconnect Reliability ◽  
Key Issues

ABSTRACTDifficulty during plasma etching and post-etch corrosion are major drawbacks of Al-Si-Cu alloy films, when used for integrated circuit interconnect. Moreover, the relatively large solute mobility of Cu in Al may lead to void formation by precipitate coarsening. As integrated circuit dimensions decrease reliability issues, such as electromigration and mechanical stress voiding, are becoming increasingly important. At present several types of Al alloys are considered as possible alternatives for Al-Si-Cu: Al-Pd, Al-Sc, Al-Pd-Cu, Al-Si-Pd, Al-Si-V, Al-Si-Sc, Al-Si-Pd-Nb, and Al-Si-V-Pd. The latter quaternary alloy has been designed such as to combine the positive aspects of both Pd and V. In comparison with Cu in Al, a) the (low temperature) solid solubility is negligible for Pd and small for V, and b) the mobility is similar for Pd, but very small for V.With transmission-electron microscopy, passivated Al-Si-Cu alloy films have been studied after thermal stressing at 200 °C: ө-Al2Cu coarsening was observed together with void condensation. Lifetests on unpassivated Al-Si-V-Pd alloys at 180 °C and 2xl06A/cm2 have shown an extremely high resistance to electromigration. Electromigration and microstructural data on these quaternary alloys will be presented. These findings suggest how the microstructure is stabilized by the combined action of the V and Pd solute atoms, a) by nm-scale (A1,V) precipitates within the Al grains and b) by small (Al,Pd) particles at the Al grain boundaries. Furthermore, the key issues in terms of reliability related microstructural phenomena are both solute and solvent mobilities in grain interiors as well as along interfaces and grain boundaries. Arguments will be given showing that at low solute concentrations the metals (V and Pd) each by themselves are not effective enough to influence the solvent motion of aluminium along interfaces and grain boundaries significantly. The combination of the two metals, however, was found to be very effective.

Grain growth behavior of a nanostructured 5083 Al–Mg alloy

2001 ◽  
Vol 16 (4) ◽  
pp. 938-944 ◽  
Author(s):  
V. L. Tellkamp ◽  
S. Dallek ◽  
D. Cheng ◽  
E. J. Lavernia
Keyword(s):  
Activation Energy ◽  
Stress Relaxation ◽  
Low Temperature ◽  
Grain Boundaries ◽  
Relaxation Process ◽  
Grain Growth ◽  
Alloy Powder ◽  
Growth Behavior ◽  
Mg Alloy ◽  
Grain Growth Behavior

A nanostructured 5083 Al–Mg alloy powder was subjected to various thermal heat treatments in an attempt to understand the fundamental mechanisms of recovery, recrystallization and grain growth as they apply to nanostructured materials. A low-temperature stress relaxation process associated with reordering of the grain boundaries was found to occur at 158 °C. A bimodal restructuring of the grains occurred at 307 °C for the unconstrained grains and 381 °C for the constrained grains. An approximate activation energy of 5.6 kJ/mol was found for the metastable nanostructured grains, while an approximate activation energy of 142 kJ/mol was found above the restructuring temperature.

Analysis of Electromigration Extrusion Failure Mode in Damascene Copper Interconnects

2001 ◽  
Vol 714 ◽  
Author(s):  
Lucile Arnaud ◽  
Gérard Tartavel ◽  
Thierry Berger ◽  
François Mondon ◽  
Robert Truche
Keyword(s):  
Failure Mode ◽  
Short Circuit ◽  
Void Formation ◽  
Chemical Vapor ◽  
Diffusion Path ◽  
Operating Conditions ◽  
Copper Interconnects ◽  
Diffusion Paths ◽  
Damascene Interconnects ◽  
Mode Failure

ABSTRACTThe electromigration performance of copper damascene interconnects has been studied with respect to hillock formation and is compared to void formation failure mode. The metal lines consisted of Chemical Vapor Deposition (CVD) copper deposited on CVD TiN and capped with SiN. SiO2 was used for copper lines insulation and final passivation. Two line widths (0.5 and 3µm) have been characterized. It is shown that higher activation energy values are obtained for void formation failure mode, respectively Ea = 0.86 eV for wide lines (poly-grain microstructure) and Ea =1.04 eV for narrow lines (quasi-bamboo microstructure) than for extrusion failure mode. Failure analysis performed with a Scanning Electron Microscope (SEM) showed that grain boundaries are active diffusion paths in polycrystalline copper lines whereas interface diffusion is believed to be the main diffusion path in narrow lines. Extrusions are shown to occur at the upper interface of copper damascene lines and to extend laterally as a consequence of cracks in dielectric layers and are thus responsible for short circuit between adjacent lines. Implications on extrapolated lifetimes at operating conditions are discussed.

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